Abstract: A tunable laser device is described. In one example, the tunable laser device includes an adaptive ring mirror, a gain waveguide, a loop mirror waveguide, and a booster amplifier waveguide. The gain waveguide and the boost amplifier waveguide can be formed in a semiconductor optical amplifier (SOA) region of the tunable laser device, and the adaptive ring mirror and the loop mirror waveguide can be formed in a silicon photonics region of the tunable laser device. The adaptive ring mirror includes a phase shifter optically coupled between a number of MMI couplers. By inducing a phase shift using the phase shifter, the wavelength of the output of the tunable laser device can be altered or adjusted for use in coherent fiber-optic communications, for example, among other applications.

Abstract: A wavelength locker includes first and second waveguides to guide light. The wavelength locker also includes a multimode interference (MMI) coupler having a number of inputs and outputs. First and second inputs of the MMI coupler are coupled to outputs of the first and second waveguides. The MMI coupler merges light from the first and second waveguides to generate an interference pattern of light. The MMI coupler then outputs a plurality of phase shifted versions of the interference pattern. The wavelength locker also includes an interference pattern selector configured to receive signals corresponding, respectively, to light output from the outputs of the MMI coupler. The interference pattern selector is also configured to select one or more outputs of the MMI coupler based on power levels of the interference patterns output from the MMI coupler and a predetermined frequency of a telecommunications frequency grid.

Abstract: A tunable laser device is described. In one example, the tunable laser device includes an adaptive ring mirror, a gain waveguide, a loop mirror waveguide, and a booster amplifier waveguide. The gain waveguide and the boost amplifier waveguide can be formed in a semiconductor optical amplifier (SOA) region of the tunable laser device, and the adaptive ring mirror and the loop mirror waveguide can be formed in a silicon photonics region of the tunable laser device. The adaptive ring mirror includes a phase shifter optically coupled between a number of MMI couplers. By inducing a phase shift using the phase shifter, the wavelength of the output of the tunable laser device can be altered or adjusted for use in coherent fiber-optic communications, for example, among other applications.

Abstract: A wavelength locker includes first and second waveguides to guide light. The wavelength locker also includes a multimode interference (MMI) coupler having a number of inputs and outputs. First and second inputs of the MMI coupler are coupled to outputs of the first and second waveguides. The MMI coupler merges light from the first and second waveguides to generate an interference pattern of light. The MMI coupler then outputs a plurality of phase shifted versions of the interference pattern. The wavelength locker also includes an interference pattern selector configured to receive signals corresponding, respectively, to light output from the outputs of the MMI coupler. The interference pattern selector is also configured to select one or more outputs of the MMI coupler based on power levels of the interference patterns output from the MMI coupler and a predetermined frequency of a telecommunications frequency grid.

Abstract: An optical module, which is arranged in an optical transmission path, includes an optical amplifying unit configured with a semiconductor, wherein the optical amplifying unit amplifies light input from the optical transmission path, and an optical element configured with a semiconductor, wherein the optical element propagates the light amplified by the optical amplifying unit to the optical transmission path.

Abstract: A gain element and a variable wavelength reflector form a resonator. A wavelength selective element selects a resonance wavelength in the resonator. A beam splitter is provided for monitoring an incident light from the gain element and a reflected light from the variable wavelength reflector. A phase adjustment element is arranged in the resonator. A wavelength-lock control unit locks the resonance wavelength to a desired resonance wavelength by adjusting the phase of the resonance wavelength based on the monitored incident light and by adjusting the variable wavelength reflector based on a ratio between the incident light and the reflected light.

Abstract: A gain element and a variable wavelength reflector form a resonator. A wavelength selective element selects a resonance wavelength in the resonator. A beam splitter is provided for monitoring an incident light from the gain element and a reflected light from the variable wavelength reflector. A phase adjustment element is arranged in the resonator. A wavelength-lock control unit locks the resonance wavelength to a desired resonance wavelength by adjusting the phase of the resonance wavelength based on the monitored incident light and by adjusting the variable wavelength reflector based on a ratio between the incident light and the reflected light.

Abstract: An electro-absorption semiconductor optical modulator comprises an n-type cladding layer of III-V compound semiconductor; a p-type cladding layer of III-V compound semiconductor; and an active region. The active region is provided between the n-type cladding layer and the p-type cladding layer, and has a quantum well structure. The quantum well structure includes plural semiconductor units, each of which has a well layer, a barrier layer and an interlayer. The interlayer is made of material of a bandgap between a bandgap of the well layer and a bandgap of the barrier layer, and the well layer is compressively strained. The well layer, interlayer and barrier layer are sequentially arranged in each semiconductor unit in a direction from the p-type cladding layer to the n-type cladding layer.

Abstract: A directional coupler type optical modulator with traveling-wave electrodes includes a first directional coupler region, a waveguide wave coupling region, a second directional coupler region, and a set of noncrossing traveling-wave electrodes disposed along the outside of the waveguides. The electrodes of each directional coupler are connected to the traveling-wave electrodes via air-bridges. The waveguide structures are of the P-I-N type having a common N-type conducting layer which provides delta-beta operation of the directional coupler, and both cross and bar states are controlled by a single input signal.

Abstract: An optical modulator includes a p- or n-type semiconductor layer that is provided at an upper part of an optical waveguide path, and modulating electrodes that are provided at intervals on the semiconductor layer in an extension area of the optical waveguide path. The semiconductor layer has first regions located immediately under the modulating electrodes, and second regions located between the first regions. The second regions have separators that electrically separate the first regions from one another.

Abstract: A plurality of semiconductor devices are disposed in a line on the surface of a supporting substrate. Each semiconductor device is adapted to generate an electric signal depending on the intensity of incident light. Adjacent semiconductor devices are optically coupled by an interconnecting optical waveguide so that light can pass through the semiconductor device one by one in a direction from a first stage closest to an input end to a last stage. An electric signal transmission line is formed of a pair of conductors connected to the semiconductor devices so that the electric signal generated by the semiconductor devices can propagate. One conductor of the pair of conductors of the electric signal transmission line is formed so as to extend in the air above the supporting substrate between adjacent semiconductor devices.

Abstract: There are provided first and second optical waveguides formed on a semiconductor substrate and having upper clad layers and core layers that are separated mutually respectively, first and second phase modulation electrodes formed on the first and second optical waveguides respectively, and first and second slot-line electrodes formed on the semiconductor substrate on both sides of the first and second optical waveguides and connected to the first and second phase modulation electrodes via air-bridge wirings separately respectively.

Abstract: An optical module, which is arranged in an optical transmission path, includes an optical amplifying unit configured with a semiconductor, wherein the optical amplifying unit amplifies light input from the optical transmission path, and an optical element configured with a semiconductor, wherein the optical element propagates the light amplified by the optical amplifying unit to the optical transmission path.

Abstract: A semiconductor optical modulator, a Mach-Zehnder optical modulator employing the same, and a method of manufacturing a semiconductor optical modulator that are suitable for high-speed baseband communication are provided. An optical waveguide core layer is formed in such a manner that it alternately crosses micro optical modulator elements and gap regions, which are formed by placing electrically insulating material at predetermined intervals on an electrically conductive substrate. The core layer is connected to a signal electrode portion via a conductive semiconductor portion in each micro optical modulator element. A ground electrode is connected to the core layer via the conductive substrate. Further, the signal electrode portions are connected in a series to form a signal electrode by means of in-between metal wirings. Conductive semiconductor material is located between the core layer and the electrodes. In the gap regions, the core layer is sandwiched between insulating semiconductor layers.

Abstract: A directional coupler type optical modulator with traveling-wave electrodes includes a first directional coupler region, a waveguide wave coupling region, a second directional coupler region, and a set of noncrossing traveling-wave electrodes disposed along the outside of the waveguides. The electrodes of each directional coupler are connected to the traveling-wave electrodes via air-bridges. The waveguide structures are of the P-I-N type having a common N-type conducting layer which provides delta-beta operation of the directional coupler, and both cross and bar states are controlled by a single input signal.

Abstract: A directional coupler type optical modulator with traveling-wave electrodes includes a first directional coupler region, a waveguide wave coupling region, a second directional coupler region, and a set of noncrossing traveling-wave electrodes disposed along the outside of the waveguides. The electrodes of each directional coupler are connected to the traveling-wave electrodes via air-bridges. The waveguide structures are of the P-I-N type having a common N-type conducting layer which provides delta-beta operation of the directional coupler, and both cross and bar states are controlled by a single input signal.

Abstract: A photo sensor is formed in a partial area of the principal surface of a substrate. The photo sensor includes a light reception layer parallel to the principal surface, the light reception layer being made of semiconductor and generating carriers in response to received light. A light waveguide is formed in a partial area of the principal surface of the substrate, the light waveguide propagating light in a direction parallel to the principal surface and introducing light into the light reception layer. A semi-insulating semiconductor film covers side faces of the photo sensor. A pair of electrodes flows current into the light reception layer of the photo sensor in a thickness direction of the light reception layer. A semiconductor light reception device having a structure suitable for high-speed operation and easy to manufacture is provided.

Abstract: An optical modulator includes a p- or n-type semiconductor layer that is provided at an upper part of an optical waveguide path, and modulating electrodes that are provided at intervals on the semiconductor layer in an extension area of the optical waveguide path. The semiconductor layer has first regions located immediately under the modulating electrodes, and second regions located between the first regions. The second regions have separators that electrically separate the first regions from one another.

Abstract: A directional coupler type optical modulator with traveling-wave electrodes includes a first directional coupler region, a waveguide wave coupling region, a second directional coupler region, and a set of noncrossing traveling-wave electrodes disposed along the outside of the waveguides. The electrodes of each directional coupler are connected to the traveling-wave electrodes via air-bridges. The waveguide structures are of the P-I-N type having a common N-type conducting layer which provides delta-beta operation of the directional coupler, and both cross and bar states are controlled by a single input signal.

Abstract: There are provided first and second optical waveguides formed on a semiconductor substrate and having upper clad layers and core layers that are separated mutually respectively, first and second phase modulation electrodes formed on the first and second optical waveguides respectively, and first and second slot-line electrodes formed on the semiconductor substrate on both sides of the first and second optical waveguides and connected to the first and second phase modulation electrodes via air-bridge wirings separately respectively.